UtshovBhagavad Gita 2.15
यं हि न व्यथयन्त्येते पुरुषं पुरुषर्षभ।
समदुःखसुखं धीरं सोऽमृतत्वाय कल्पते।।2.15।।
Yam hi na vyathayantyete purusham purusharshabha
Samaduhkhasukham dhiram somritatvaya kalpate
Simple meaning, written by AIOne who is not disturbed by pleasure or pain, who remains steady, is considered to attain immortality.